Using springwater for heatpump source

I have a three -tile spring that prodices about 5 gallons/min and a storage capacity of 262 gallons. It produces 15-20 psi at the house(it sets above the house about 75 feet. I have investigated the needs of a 5 ton unit (about 1.5 gal/ton). What I cant find is how long will a typical run of the heat pump be..ie. between storage and gpm can I use the spring water to run this system.I do have to check on the temperature again, But other wise???